<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <title>Document</title>
</head>
<body>
  <div>1</div>
  <div>2</div>
  <div>3</div>
  <div>4</div>
  <div>5</div>
  <div>6</div>
  <script>
    var oDivs = document.getElementsByTagName('div');
    console.log(oDivs);	// HTMLCollection(6) [div, div, div, div, div, div]
    var ary = [...oDivs];
    ary.push('a');		// 在数组中追加a
    console.log(ary);	// (7) [div, div, div, div, div, div, "a"]
  </script>
</body>
</html>